Pneumocystis carinii pneumonia complicating methotrexate treatment of primary sclerosing cholangitis.

The etiology of primary sclerosing cholangitis, a chronic progressive cholestatic liver disease, is poorly understood. Treatment with oral methotrexate may improve patient symptoms, liver biochemistry, and hepatic histology. This report describes a severe life-threatening complication of methotrexate therapy in primary sclerosing cholangitis--the development of Pneumocystis carinii pneumonia. The reported cases of methotrexate-associated P. carinii pneumonia in the literature are reviewed. With the increasing use of methotrexate in chronic inflammatory disorders, physicians should be aware of this potentially lethal complication.